Various devices detect, monitor and/or control the level of liquids. However, when the liquids whose levels are being detected, monitored and/or controlled are viscous (e.g., printing inks), problems are often encountered. For example, level monitoring devices for viscous liquids are generally quite complex. In addition, it is often difficult to easily and efficiently clean these complex devices; thus, increasing the possibility of false readings.
Notwithstanding the above, there are many different industries wherein it is critical to monitor the supply and/or level of viscous liquid. One example of an industry where liquid levels play a vital role is the printing industry.
In the printing industry, printing ink (a relatively viscous liquid) is often applied to a stencil (e.g., an impression cylinder). While there are many different ways in which to apply ink to such stencils, one of the more common approaches is to employ an ink distribution system. For example, a metering roll (e.g., an Anilox metering roll), which directly or indirectly comes into contact with an ink supply, is often used.
Flexography is one specific type of a printing process which often employs the use of metering rolls. In flexographic printing processes, ink is generally pumped from an ink source into an ink fountain or well until the level of ink reaches a predetermined full position.
As the metering roll rotates, it picks up ink from the full fountain. A doctor blade assembly is then often employed to control the amount of ink adhering to the outer surface of the metering roll.
Since ink is continually being picked up by the metering roll and ultimately distributed to the surface being printed, it is necessary to have a constant supply of ink to the fountain in order to maintain the "full" position. Maintaining a "full" position is often critical since, in many instances, if the ink level within the fountain falls below that predetermined full position, the particular printing process will be adversely affected. Accordingly, under these circumstances it is necessary to employ some sort of ink level detecting system. However, as stated above, most liquid level detecting devices are not adequate for measuring the level of viscous liquids such as printing inks. Moreover, those which do exist, are generally quite complex and difficult to clean. In view of the above, the printing industry would greatly welcome an improved, yet simplified, method for detecting, monitoring and/or controlling the level of viscous liquids such as printing inks. Such a device would also be greatly welcomed by other industries where it is necessary to detect, monitor and/or control the level of viscous liquids.